At the time, voters had to produce a birth certificate, social security card or other documentation to qualify for a free non-driver ID to use for voting.

While opponents say the law would keep minorities away from the polls, proponents say the goal is to prevent voter fraud.

"The courts have found that simply the idea that there might be a slight inconvenience, that you have to go someplace to get an ID, is not a barrier to voting. It isn't preventing anyone from being able to vote," said Nils Frederiksen, of the Office of General Counsel.

The trial is expected to last two weeks and bring dozens of witnesses to the stand.